If you've ever noticed that the car ahead of you in traffic seems to be driving itself, there's a good chance that the person driving it is elderly. Shrinking in height as we age is quite normal, and some people start to get shorter starting at about the age of 30. Only about 20% of the population does not noticeably shrink, which is due to a combination of good genetics and a healthy lifestyle.
Not only do we shrink with age, but our height also varies considerably each day, by up to three-quarters of an inch. The vertebral discs that are sandwiched between the vertebrae, and which act as shock absorbers for the spine, are composed of up to 88% water.
In the course of our daily activities, this water is slowly squeezed out of these discs every time the spine moves. Then when we are lying down at night in bed and pressure is taken off the discs, the disks reabsorb the expelled water, similar to a sponge. So it's likely you are somewhat taller when you first get up in the morning than you are at the end of the day.
With age, a number of degenerative processes can interfere with keeping the vertebral discs properly hydrated, causing them to become less pliable. In addition, bone degeneration can contribute to the gradual collapse of the vertebrae, particularly in the upper back, which causes what's referred to as "dowager's hump," that can take some inches off your height.
Studies have found that men lose and average of 1.2 inches in height between the ages of 30 and 70, and 2 inches in total by age 80. By comparison, women lose 2 inches in height between age 30 and 70 and a total of 3 inches by age 80.
While genetics plays the largest role in how much you shrink as you age, lifestyle choices can make a significant difference as well. Those who smoke, are obese, have diabetes, get little aerobic exercise, drink excessive amounts of alcohol and caffeine and who do not follow a healthy diet are at greater risk of losing a significant amount of height as they age.
And while losing some height as we age is normal, losing too much over a short period of time can be an indicator of a more serious health condition. It is not unusual to shrink in height by a quarter inch to a third of an inch each decade after the age of 40.
However, if you are a man between the ages of 45 and 65 and notice that you are shrinking, you should see your doctor. Rapid loss of height in men can be an indicator of heart disease and can suggest they are at greater risk of a fracture of the spine or hip.
A study published in the Journal of Bone and Mineral Research found that men who lose two or more inches within two years after age 70 have a 54% greater risk of a hip fracture, and women have a 21% greater risk.
Another study published in the Archives of Internal Medicine found that men who had shrunk 1.2 inches or more over a 20-year span had a 46% greater likelihood of heart disease and were 64% more likely to die from any cause.
The best way to help preserve your height is to eat a balanced diet that is rich in calcium and vitamin D and to get plenty of exercise, particularly weight-bearing exercise (which includes walking and running), which helps to keep bones strong.